You could use advance filter, unique entries to a different area to get a count.
Or use a fancy formula courtesy of Aladin
=SUM(IF(FREQUENCY(MATCH(A1:A10,A1:A10,0),MATCH(A1:A10,A1:A10,0))>0,1))
adjust A1:A10 to suit your range. Do not however, default put in rows such as A:A, etc.
good luck
Make a unique list of manufacturers in a separate column, say in F from F2 on (using e.g., Advanced Filter ).
Lets say that the names of manufacturers are in A.
In G2 enter: =COUNTIF(A:A,F2)
Doubble click on the little black square of G2 in order to copy down the formula as far as required.
Aladin
some day I will read the question asked, but not today
that formula provides you with the count of unique entries. See Aladin's post above for more detail on the filter and countif
sorry